# Multivariable Calculus + Physics help

APC40
Hi all, I am a university student taking Calculus II at the moment. The course sometimes use physics examples, however I do not have any physics background. So I am reaching out to you guys to help me through this math question.

## Homework Statement

A baseball is hit from 4ft above home plate with an initial velocity $$\vec v(0)=40 \vec i+12 \vec j(ft/s)$$ (horizontally 40ft/s and vertically 12ft/s). Neglect all forces other than gravity, $$g=32ft/s^2$$
(a) How far does the ball travel horizontally?
(b) Find the maximum height reached.

## Homework Equations

Equations, posted again, are $$\vec v(0)=40 \vec i+12 \vec j(ft/s)$$ and $$g=32ft/s^2$$

## The Attempt at a Solution

I googled and found the equation $$v=gt+v_i$$ but I'm not sure if this is the right one, or how to proceed with this. Please advise.

Last edited:

## Answers and Replies

Science Advisor
Homework Helper
Gold Member
Hi all, I am a university student taking Calculus II at the moment. The course sometimes use physics examples, however I do not have any physics background. So I am reaching out to you guys to help me through this math question.

## Homework Statement

A baseball is hit from 4ft above home plate with an initial velocity $$\vec v(0)=40 \vec i+12 \vec j(ft/s)$$ (horizontally 40ft/s and vertically 12ft/s). Neglect all forces other than gravity, $$g=32ft/s^2$$
(a) How far does the ball travel horizontally?
(b) Find the maximum height reached.

## Homework Equations

Equations, posted again, are $$\vec v(0)=40 \vec i+12 \vec j(ft/s)$$ and $$g=32ft/s^2$$

## The Attempt at a Solution

I googled and found the equation $$v=gt+v_i$$ but I'm not sure if this is the right one, or how to proceed with this. Please advice.

That's "advise", not "advice".

Start with the acceleration ##\vec A = 0i - 32j##, integrate twice and use your initial position and velocity to evaluate the constants to get the equations of motion.